Amount of substance
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Give the formula for atom economy.
% atom economy = mass of desired product/total mass of reactants x 100
Define avogdro constant.
The number of particles in 1 mole of a substance.
What is empirical formula?
A formula that gives the simplest whole number ratio of atoms of each element in a compound.
What is the equation for ideal gas?
pV=nRT
Give the formula for percentage yield.
%y= actual yield/theoretical yield x 100
What is relative atomic mass?
Average mass of one atom of an element/ 1/12th the mass of a 12C atom
What is relative molecular mass?
Average mass of one molecule/1/12th the mass of a 12C atom
What is the equation for density?
D=M/V
What is the equation for moles?
Moles= mass(g)/MR
What is the conversion from tonnes to kg?
x1000
What is the equation for concentration?
C=M/V
What is the conversion to get dm3 from cm3
divide by 1000
Describe how to make a standard solution.
a) Weigh the sample bottle (weighing boat) containing the solid on a 2dp balance b)Transfer the beaker and reweigh sample bottle c) Record the difference in mass d) add distilled water e) stir with a glass rod until all the solid has dissolved f) transfer to volumetric flask using a funnel g) wash the funnel with distilled water h) make up to 250cm3 so that the meniscus is just under the mark i) put a stopper on the volumetric flask and shake
Describe how to preform a titration.
• Fill a burette with the acid of known concentration • Accurately measure out 25cm3 of the alkali standard solution using a pipette and transfer to a conical flask • Add a few drops of suitable indicator to the alkali • Slowly add the acid from the burette into the conical flask, swirling constantly. As soon as the indicator chnages colour the solution has turned neutral so stop adding the acid. Record the volume of acid which has been added. • Repeat the process until you get two results which are within 0.1cm3 of each other. The mean of these two results are then used to calculate an average titre as they are concordant. • Once the average titre has been determined it can be used to calculate the unknown concentration.
What is the limiting factor?
The substance in a chemical reaction that is used up first. It is the one with the least moles.
What is the equation for percentage uncertainty (% error)
% uncertainty = error of equipment x no. of times it was used/ amount measured x 100
Outline the units for each part of the ideal gas equation.
P= Pa V= m3 T= K
How do you convert from kPa to Pa?
x 1000
How do you convert from cm3 to m3?
divide by 1,000,000
How do you convert from dm3 to m3?
divide by 1000
How do you convert from degrees Celsius to K?
add 273 to value
How do you know all the water has evaporated in water of crystallisation?
When you keep reheating and you get a constant mass after doing so.
How do you improve atom economy?
Find a use for the other products, that way a greater proportion of the reactants will be turned into useful products.
What is the atom economy of a reaction with only one product?
100% as all the reactants are converted into product.